According to a report from Bloomberg (via AllThingsD), the U.S. Federal Trade Commission subpoenaed Apple as part of its antitrust investigation of Google. There are not many details currently, but the report claims the FTC is interested in Apple’s agreement with the company to use Google as its primary default search engine on iOS devices.

The agency’s request for documents includes the agreements that made Google the preferred search engine on Apple’s mobile devices, said the people, who weren’t authorized to speak publicly and declined to be identified. Google rivals such as Microsoft Corp. (MSFT) have criticized these agreements as anticompetitive.